The present invention relates to production of control samples for use during testing for steroid receptors in human tissue. It is current medical theory that various steroid hormones such as glucocorticoids and mineralocorticoids and even those hormones which are normally considered sex hormones such as androgens, estrogens and progestins are present in both male and female humans. It is further medical theory that proteins called receptors are present in target cells within specific organs which selectively attract or hold the various steroid hormones within the particular organ.
It is often medically important to determine whether particular receptors are present in certain tissue in a human. In particular, it has been found that various steroids may be advantageously utilized to treat carcinoma. In the past cancer has frequently been attacked by utilization of cytotoxic chemotherapy or radiation therapy under the premise that, although chemotherapy or radiation kills a certain number of non-cancerous cells throughout the body, this treatment will kill a higher percentage of the cancerous cells and thereby, presumably, control or eradicate the cancer. In this process the damage to healthy tissue within the body can be extensive. Therefore, it is desirable to find a substance which will be selectively toxic to cancerous cells.
One particular way of treating cancerous cells in a specific manner, has been the development of what is called endocrine therapy wherein steroid hormones are utilized to attack cancerous growths in specific organs. A secondary advantage of such treatment is that, even if the cancer metastasizes and begins to spread throughout the body, the cancerous cells will still have the particular receptors of the organ from which the cancer originated and, therefore, will be selectively attacked by the hormones. Unfortunately, it has been found that many cancerous tumors at some stage of their development modify the structure of the cells therein so as to preclude the receptors and/or their production.
If the receptors are not present in the cancerous cells, then endocrine therapy will at best be a waste of time and may actually do more damage than good. If the receptors are not present, it is important to determine this early so that other treatment such as chemotherapy or radiological treatment can be initiated as soon as possible. Thus, it has become important to assay a cancerous tumor in order to determine whether any of the desired receptors are present. It is further important to ensure that any test related to presence of receptors in such tissue include simultaneous testing of known control samples so as to ensure the accuracy of the assay. The various steroid hormone receptors are in common supply in mammal tissue, especially in organs which are activated by a specific steroid hormone. Unfortunately, the receptor protein is extremely heat labile and is very easily destroyed or rendered inert by separation from its parent live tissue for even short periods of time at room temperature. Freezing the tissue containing the receptor to a temperature in a range of solid carbon dioxide or liquid nitrogen at atmospheric pressures will maintain the vitality of the protein for a longer period of time but does not provide a suitable sample with which to work and requires cumbersome cryogenic packaging and short travel time to prevent warming and destruction of the sample. The process of the present invention provides for production of a comparison sample which is in a form which is easy to use, vital for long periods of time, and can be stored at room temperature.
Of particular interest in the area of endocrine therapy is the treatment of breast cancer with progesterone or estrogen hormones by processes, as described above. In particular, it has been found in certain medical testing that patients with breast cancer having a high estrogen receptor value respond poorly to chemotherapy as compared to patients with low estrogen receptor values. For instance, on a whole, women before menopause respond to chemotherapy with a substantially lower success rate than women who are post menopausal. Also, patients with high estrogen receptor values respond very favorably to endocrine therapy, whereas those with low receptor values respond very poorly to endocrine treatment. It is therefore important for an attending physician to determine whether estrogen receptors are abundant within the breast tumor. It is noted that estrogen receptors may be present in breast cancers of both men and women.
It is also a current medical theory that estrogen receptors in some manner facilitate or induce the formation of progesterone receptors. At lower or zero estrogen receptor levels progesterone receptors are apparently not produced at all, therefore, a test for progesterone receptors is often desirable to ensure relatively high levels of estrogen receptors.